title: Use of Individual-level Covariates to Improve Latent Class Analysis of Trypanosoma Cruzi Diagnostic Tests.
abstract: Statistical methods such as latent class analysis can estimate the sensitivity and specificity of diagnostic tests when no perfect reference test exists. Traditional latent class methods assume a constant disease prevalence in one or more tested populations. When the risk of disease varies in a known way, these models fail to take advantage of additional information that can be obtained by measuring risk factors at the level of the individual. We show that by incorporating complex field-based epidemiologic data, in which the disease prevalence varies as a continuous function of individual-level covariates, our model produces more accurate sensitivity and specificity estimates than previous methods. We apply this technique to a simulated population and to actual Chagas disease test data from a community near Arequipa, Peru. Results from our model estimate that the first-line enzyme-linked immunosorbent assay has a sensitivity of 78% (95% CI: 62-100%) and a specificity of 100% (95% CI: 99-100%). The confirmatory immunofluorescence assay is estimated to be 73% sensitive (95% CI: 65-81%) and 99% specific (95% CI: 96-100%).
authors.affiliation: Vanderbilt University School of Medicine.
authors.forename: Aaron W
authors.initials: AW
authors.lastname: Tustin
authors.forename: Dylan S
authors.initials: DS
authors.lastname: Small
authors.forename: Stephen
authors.initials: S
authors.lastname: Delgado
authors.forename: Ricardo Castillo
authors.initials: RC
authors.lastname: Neyra
authors.forename: Manuela R
authors.initials: MR
authors.lastname: Verastegui
authors.forename: Jenny M
authors.initials: JM
authors.lastname: Ancca Juárez
authors.forename: Víctor R
authors.initials: VR
authors.lastname: Quispe Machaca
authors.forename: Robert H
authors.initials: RH
authors.lastname: Gilman
authors.forename: Caryn
authors.initials: C
authors.lastname: Bern
authors.forename: Michael Z
authors.initials: MZ
authors.lastname: Levy
keywords: Chagas disease; Trypanosoma cruzi; latent class analysis